Aluminum offset printing plate

ABSTRACT

AN ALUMINUM PRINTING PLATE FOR USE IN OFFSET ROLLER PLATING IS MADE OF AN ALUMINUM BASE ALLOY INCLUDNG THE FOLLOWING ALLOYING COMPONENTS:   PERCENT MAGNESIUM 0.8-2.5 SILCON 0.2-0.4 MANGANESE 0.8-1.4 COPPER 0.05-0.3 IRON 0.2-0.6 ZINC 0.01-0.2 ALUMINUM BALANCE

United States Patent O 3,672,878 ALUMINUM OFFSET PRINTING PLATE AdolfTeubler, Uedorf, near Bonn, and Paul Eversheim,

Bonn, Germany, assignors to Vereinigte Leichtmetall- Werke G.m.b.H.,Bonn, Germany No Drawing. Filed Sept. 24, 1969, Ser. No. 860,805 Claimspriority, application Germany, Sept. 27, 1968, P 17 83 066.9; June 9,1969,P 19 29 146.4 Int. Cl. C22c 21/04 US. Cl. 75141 4 Claims ABSTRACTOF THE DISCLOSURE An aluminum printing plate for use in offset rollerplating is made of an aluminum base alloy including the followingalloying components:

Percent Magnesium 0.8-2.5 Silicon 0.2-0.4 Manganese 0.8-1.4 Copper0.05-0.3 Iron 0.2-0.6 Zinc 0.01-0.2 Aluminum Balance BACKGROUND OF THEINVENTION A material consisting of aluminum as the base material with apurity of 99% and more has already been used for printing plates inoffset printing, particularly for single-color prints. However, theseplates were not suitable for so-called roller offset printing. If thealuminum plate or sheet has a tensile strength of about 16 to 18 kp./mm.as required to obtain the necessary stability and rigidity, the dangerof tearing of the sheet at the sharp-angled clamping edges issubstantial. These edges, however, are necessary for the narrow, tightclamping of the offset plates on the rollers of the printing machine. Atearing of the sheet is particularly obnoxious if it occursnot duringthe initial angling of the edges or during the clamping butby virtue ofthe centrifugal force during actual operation such as results from thehigh rotation speed of the printing cylinder.

'It is therefore an object of the present invention to provide forprinting plates for offset roller printing processes which (a) have ahigh rigidity to be stored in upstanding position and also to assureform stability during high rotation speeds; (b) are sufficientlyflexible to permit that the plates, when clamped on the printingcylinder, conform smoothly and exactly to the surface of the cylinder;and (c) have good angling properties so as to prevent tearing during theacute angle folding or subsequently when subjected to a high tensilestress.

SUMMARY OF THE INVENTION These objects are met by an offset printingplate which consists of an aluminum base alloy and includes thefollowing alloying components in the following percentages by referenceto the weight of the total composition Percent Magnesium 0.8-2.5 Silicon0.2-0.4 Manganese 0.8-1.4 Copper 0.05-0.3 Iron 0.2-0.6 Zinc 0.01-0.2Aluminum Balance DESCRIPTION OF THE PREFERRED EMBODIMENTS In addition tothe components listed above, the print- 3,672,878 Patented June 27, 1972"ice ing plate of the invention may also include 0.01 to 0.05% titanium,and 0.001 to 0.005% boron.

The preferred composition for the printing plates would be as follows:

Another preferred embodiment would be constituted as just described, butwould additionally include 0.03% titanium and 0.003% boron.

The general mechanical properties of the alloys used according to theinvention for the printing plate appear from the following combination:

Soft condition I Yield point: 5 16-24 kp./mm. Tensile strength: 6 17-22kp./mm. Elongation: 6 15-30% Intermediate hard condition Yield point: 6=l6-24 kp/mm. Tensile strength: 6 :20-28 kpJmm. Elongation: 6 =8-l5%These properties will afford a high rigidity, permitting to store theplates in upstanding position. It will also assure that the plates arenot subject to deformation during the high rotation speeds.

The alloy furthermore has a sufficient flexibility. The platestherefore, when clamped onto the printing cylinder, can be made toconform completely to the cylinder.

These alloys also give the printing plates a good angling property. As aresult, the plates will not be subject to tearing when they are clampedonto the cylinder and the acute angle edges are being formed. Also,during operation, when the plates are subject to substantial tensilestress, they will not have a tendency to tear at the clamped edges.

Preferably, the aluminum base plates formed as described are provided onboth major faces with plating layers. These layers may be applied byconventional roller plating processes. The plating may for instanceconsist of pure aluminum of a degree of purity between 99 and 99.9%.Preferably, the plating layer has a thickness between 2 and 16% relativeto the thickness of the entire plate. The thickness just stated for thelayer applies to each separate plating layer. The ofliset plate may beanodized. Particularly preferred would be an aluminum plating of apurity of about 99.4%

However, the plates most preferably are provided with plating layers onboth major faces which layers are composed like the principal material,that is, the aluminum coating contains the same components as the corematerial but in different percentages. The total plating layers may forinstance have a thickness of about 8% relative to the total thickness ofthe entire plate. The total plate may for instance after plating have athickness of 0.50

The following examples will further illustrate the invention.

EXAMPLE 1 An aluminum offset printing plate was formed by plating in aroller plating process an aluminum core with layers having a combinedthickness of about 8% of the total thickness of the plate. The totalthickness was 0.50 mm.

The composition of the aluminum alloy employed was as follows (allpercentages relative to weight of the total composition) Core element:Percent Copper 0.15 Manganese 1.10 Magnesium 1.12 Silicon 0.30

Iron 0.45

Zinc 0.05

Titanium 0.01

Boron 0.003

Aluminum Balance Plating layers: Percent Copper 0.01 Manganese 0.02Magnesium 0.0 1 Silicon 0.18

'Iron 0.41 Zinc 0.07

The properties obtained with this type of plate were as follows:

Yield point: 21.0 kp./mm.

Tensile strength: 24 kp./mm. Elongation: 8%

EXAMPLE 2 The same type of printing plate was formed as described inExample 1. However, the composition of the core material and platinglayers was as follows:

The printing plate of this example had the following properties -Yieldpoint: 24 kp./mm.

Tensile strength 28 kp./mm. Elongation: 6%

EXAMPLE 3 An offset printing plate was again formed as described inExample 1 with the following ditference in the composition of thealloys:

Core material: Percent Copper 0.14 Manganese 1.12 Magnesium 1.6 Silicon0.25

Iron 0.35 Zinc 0.06 Titanium 0.011

Boron 0.002

Aluminum Balance 4 Plating layers: Percent Copper 0.002

Manganese 0.005

Magnesium 0.004

Silicon 0.20

Iron 0.40

Zinc 0.03

Aluminum Balance The printing plate of this example had the followingproperties:

Yield point: 13 kp./mm. Tensile strength: 23 kp./mm. Elongation: 18%

The printing plates of all three examples as above described hadexcellent properties for roller oflset printing and were generallyconsidered acceptable by the printers.

We claim:

1. An aluminum printing plate for use in offset roller printing, theplate consisting of an aluminum base alloy including the followingalloying components:

' Percent Magnesium 0.8-2.5

Silicon 0.20.4

Manganese 0.8-1.4

Copper 0.05-0.3

Iron 0.2-0.6

Zinc 0.01-0.2

Aluminum Balance 2. The printing plate of claim 1 which includes 0.01 to0.05% titanium and 0.001 to 0.005% boron.

3. The printing plate of claim 1 wherein the aluminum base alloyincludes the following alloying components in the following percentages:

Percent Magnesium 1.5

Silicon 0.3

Manganese 1.1

Copper 0.15

Iron 0.4

Zinc 0.1

4. The printing plate of claim 3, which includes 0.03% titanium and0.003% boron.

References Cited UNITED STATES PATENTS 3,490,955 1/ 1970 Winter et al-141 X 2,240,732 5/1941 Wood 101-458 X 2,290,016 7/1942 Bonsack 75-1412,290,025 7/1942 Bonsack 75-141 2,922,731 1/ 1960 Rutemiller 75-141 XFOREIGN PATENTS 1,206,596 9/ 1965 Germany.

L. DEWAYNE RUTLEDGE, Primary Examiner E. L. WEISE, Assistant ExaminerUS. Cl. X.R. 101-459

